Abstract

Food waste contains numerous easily degradable components, and anaerobic digestion is prone to acidification and instability. This work aimed to investigate the effect of adding yeast on biogas production performance, when substrate is added after biogas production is reduced. The results showed that the daily biogas production increased 520 and 550 ml by adding 2.0% (volatile solids; VS) of activated yeast on the 12th and 37th day of anaerobic digestion, respectively, and the gas production was relatively stable. In the control group without yeast, the increase of gas production was significantly reduced. After the second addition of substrate and yeast, biogas production only increased 60 ml compared with that before the addition. After fermentation, the biogas production of yeast group also increased by 33.2% compared with the control group. Results of the analysis of indicators, such as volatile organic acids, alkalinity and propionic acid, showed that the stability of the anaerobic digestion system of the yeast group was higher. Thus, the yeast group is highly likely to recover normal gas production when the biogas production is reduced, and substrate is added. The results provide a reference for experiments on the industrialization of continuous anaerobic digestion to take tolerable measures when the organic load of the feed fluctuates dramatically.

Highlights

  • Food waste contains numerous degradable components, and anaerobic digestion is prone to acidification and instability

  • The ethanol could be gradually converted into acetic acid, which can be used by methanogens, thereby increasing methane production and enabling the stable operation of anaerobic fermentation [4]

  • The effect of yeast addition on Anaerobic digestion (AD) of Food waste (FW) was investigated in this study

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Summary

Introduction

Food waste contains numerous degradable components, and anaerobic digestion is prone to acidification and instability. In the process of anaerobic digestion of food waste, yeast can convert the degradable organic matter of substrates into neutral ethanol instead of acid propionic acid or butyric acid, which reduces the load of VFAs in the system [6,23]. Through the addition of yeast to the FW substrate for ethanol pre-fermentation before AD, a large amount of ethanol is produced, and ethanol is gradually converted into acetic acid, which in turn can be used by methanogens, thereby increasing methane production, reducing the effect of acidification on the system and enhancing the stability of AD [15,24]. The effect of yeast addition on the methane production from FW in AD system was conducted

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